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Over 1.4 million people are diagnosed with colorectal cancer (CRC) each year, making it the third most common cancer in the world. Increased screening and therapeutic modalities including improved combination treatments have reduced CRC mortality, although incidence and mortality rates are still increasing in some areas. Serum-based biomarkers are mainly used for follow-up of cancer, and are ideal due to the ease and minimally invasive nature of sample collection. Unfortunately, CEA and other serum markers have too low sensitivity for screening and preoperative diagnostic purposes. Increasing interest is focused on the possible use of biomarkers for predicting treatment response and prognosis in cancer. In this study, we have performed mass spectrometry analysis (UPLC-UDMSE) of serum samples from 19 CRC patients. Increased levels of C-reactive protein (CRP), which occur during local inflammation and the presence of a systemic inflammatory response, have been linked to poor prognosis in CRC patients. We chose to analyze samples according to CRP values by dividing them into the categories CRP <30 and >30, and, separately, according to short and long 5-year survival. The aim was to discover differentially expressed proteins associated with poor prognosis and shorter survival. We quantified 256 proteins and performed detailed statistical analyses and pathway analysis. We discovered multiple proteins that are up- or downregulated in patients with CRP >30 as compared to CRP <30 and in patients with short as compared to long 5-year survival. Pathways that were enriched include LXR/RXR activation, FXR/RXR activation, complement and coagulation cascades and acute phase signaling response, with some of the proteins we identified having roles in these pathways. In this study, we have identified multiple proteins, of which a few have been previously identified as potential biomarkers, and others that have been identified as potential biomarkers for CRC for the first time, to the best of our knowledge. While these proteins still need to be validated in larger patient series, this pilot study will pave the way for future studies aiming to provide better biomarkers for patients with CRC. [ABSTRACT FROM AUTHOR]

Anti-EGFR therapy is commonly used to treat colorectal cancer (CRC), although only a subset of patients benefit from the treatment. While KRAS mutation predicts non-responsiveness, positive predictive markers are not in clinical practice. We previously showed that immunohistochemistry (IHC)-guided EGFR gene copy number (GCN) analysis may identify CRC patients benefiting from anti-EGFR treatment. Here we tested the predictive value of such analysis in chemorefractory metastatic CRC, elucidated EGFR GCN heterogeneity within the tumors, and evaluated the association between EGFR GCN, KRAS status, and anti-EGFR antibody response in CRC cell lines. The chemorefractory patient cohort consisted of 54 KRAS wild-type (WT) metastatic CRC patients. EGFR GCN status was analyzed by silver in situ hybridization using a cut-off value of 4.0 EGFR gene copies/cell. KRAS-WT and KRAS mutant CRC cell lines with different EGFR GCN were used in in vitro studies. The chemorefractory CRC tumors with EGFR GCN increase (≥4.0) responded better to anti-EGFR therapy than EGFR GCN (<4.0) tumors (clinical benefit, P = 0.0004; PFS, HR = 0.23, 95% CI 0.12–0.46). EGFR GCN counted using EGFR IHC guidance was significantly higher than the value from randomly selected areas verifying intratumoral EGFR GCN heterogeneity. In CRC cell lines, EGFR GCN correlated with EGFR expression. Best anti-EGFR response was seen with KRAS-WT, EGFR GCN = 4 cells and poorest response with KRAS-WT, EGFR GCN = 2 cells. Anti-EGFR response was associated with AKT and ERK1/2 phosphorylation, which was effectively inhibited only in cells with KRAS-WT and increased EGFR GCN. In conclusion, IHC-guided EGFR GCN is a promising predictor of anti-EGFR treatment efficacy in chemorefractory CRC. [ABSTRACT FROM AUTHOR]

Different genetic aberrations of BRAF have been reported in various malignancies. BRAF is member of the RAS/RAF/MEK/ERK pathway and constitutive activity of this pathway can lead to increased cellular growth, invasion, and metastasis. The most common activating BRAF mutation in colorectal cancer is the V600E mutation, which is present in 5-15% of all tumors, and up to 80% of tumors with high microsatellite instability (MSI) harbor this mutation. BRAF mutation is associated with proximal location, higher age, female gender, MSI-H, high grade, and mucinous histology, and is a marker of poor prognosis in colorectal cancer. The role of BRAF mutation as a predictive marker in respect of EGFR targeted treatments is controversial. BRAF V600 selective inhibitors have been approved for the treatment of V600 mutation positive metastatic melanoma, but the response rates in colorectal cancer are poor. This might be due to innate resistance mechanisms of colorectal cancers against the treatment solely targeting BRAF. To overcome resistance the combination of treatments, simultaneous inhibition of BRAF and MEK or PI3K/mTOR, might emerge as a successful therapeutic concept. [ABSTRACT FROM AUTHOR]

Frameshift mutations frequently accumulate in microsatellite-unstable colorectal cancers (MSI CRCs) typically leading to downregulation of the target genes due to nonsense-mediated messenger RNA decay. However, frameshift mutations that occur in the 3′ end of the coding regions can escape decay, which has largely been ignored in previous works. In this study, we characterized nonsense-mediated decay-escaping frameshift mutations in MSI CRC in an unbiased, genome wide manner. Combining bioinformatic search with expression profiling, we identified genes that were predicted to escape decay after a deletion in a microsatellite repeat. These repeats, located in 258 genes, were initially sequenced in 30 MSI CRC samples. The mitotic checkpoint kinase TTK was found to harbor decay-escaping heterozygous mutations in exon 22 in 59% (105/179) of MSI CRCs, which is notably more than previously reported. Additional novel deletions were found in exon 5, raising the mutation frequency to 66%. The exon 22 of TTK contains an A9–G4–A7 locus, in which the most common mutation was a mononucleotide deletion in the A9 (c.2560delA). When compared with identical non-coding repeats, TTK was found to be mutated significantly more often than expected without selective advantage. Since TTK inhibition is known to induce override of the mitotic spindle assembly checkpoint (SAC), we challenged mutated cancer cells with the microtubule-stabilizing drug paclitaxel. No evidence of checkpoint weakening was observed. As a conclusion, heterozygous TTK mutations occur at a high frequency in MSI CRCs. Unexpectedly, the plausible selective advantage in tumourigenesis does not appear to be related to SAC. [ABSTRACT FROM AUTHOR]

Homozygosity for the G allele of rs6983267 at 8q24 increases colorectal cancer (CRC) risk ∼1.5 fold. We report here that the risk allele G shows copy number increase during CRC development. Our computer algorithm, Enhancer Element Locator (EEL), identified an enhancer element that contains rs6983267. The element drove expression of a reporter gene in a pattern that is consistent with regulation by the key CRC pathway Wnt. rs6983267 affects a binding site for the Wnt-regulated transcription factor TCF4, with the risk allele G showing stronger binding in vitro and in vivo. Genome-wide ChIP assay revealed the element as the strongest TCF4 binding site within 1 Mb of MYC. An unambiguous correlation between rs6983267 genotype and MYC expression was not detected, and additional work is required to scrutinize all possible targets of the enhancer. Our work provides evidence that the common CRC predisposition associated with 8q24 arises from enhanced responsiveness to Wnt signaling. [ABSTRACT FROM AUTHOR]

Background & Aims: Gastrointestinal juvenile polyps may occur in juvenile polyposis syndrome (JPS) or sporadically. JPS is an autosomal-dominant condition caused by a germline defect in SMAD4 or BMPR1A in 50% to 60% of cases, and is characterized by multiple juvenile polyps, predominantly in the colorectum. JPS has an increased risk of gastrointestinal malignancy but sporadic juvenile polyps do not. Cyclooxygenase-2 (COX-2) expression is increased in gastrointestinal tumorigenesis and familial adenomatous polyposis. Inhibition of COX-2 leads to regression of colorectal adenomas in familial adenomatous polyposis patients and inhibits gastrointestinal tumorigenesis. To investigate the role of COX-2 in juvenile polyps, we compared the expression of COX-2 in juvenile polyps from a well-defined group of juvenile polyposis patients and sporadic juvenile polyps. Methods: COX-2 expression was assessed in 24 genetically well-defined JPS patients and 26 patients with sporadic juvenile polyps using tissue microarray analysis. Two additional markers, Hu-antigen R, a stabilizer of messenger RNA, and CCAAT/enhancer-binding protein β, a transcription factor, both associated with increased COX-2 expression, also were investigated. Results: Increased COX-2 expression in JPS patients was noted compared with patients with sporadic juvenile polyps (P < .001). Also, JPS patients with a BMPR1A germline defect had higher COX-2 expression than did JPS patients in whom no germline mutation was detected. High COX-2 levels correlated with increased cytoplasmic Hu-antigen R expression in JPS polyps (P = .022), but not in sporadic juvenile polyps. Conclusions: Juvenile polyposis and sporadic juvenile polyps show distinctive expression profiles of COX-2 that may have clinical implications. [Copyright &y& Elsevier]

A recent study described a recessive ATPase activating germ-line mutation in smooth-muscle myosin (smmhc/myh11) underlying the zebrafish meltdown (mlt) phenotype. The mlt zebrafish develops intestinal abnormalities reminiscent of human Peutz-Jeghers syndrome (PJS) and juvenile polyposis (JP). To examine the role of MYH11 in human intestinal neoplasia, we searched for MYH11 mutations in patients with colorectal cancer (CRC), PJS and JP. We found somatic protein-elongating frameshift mutations in 55% of CRCs displaying microsatellite instability and in the germ-line of one individual with PJS. Additionally, two somatic missense mutations were found in one microsatellite stable CRC. These two missense mutations, R501L and K1044N, and the frameshift mutations were functionally evaluated. All mutations resulted in unregulated molecules displaying constitutive motor activity, similar to the mutant myosin underlying mlt. Thus, MYH11 mutations appear to contribute also to human intestinal neoplasia. Unregulated MYH11 may affect the cellular energy balance or disturb cell lineage decisions in tumor progenitor cells. These data challenge our view on MYH11 as a passive differentiation marker functioning in muscle contraction and add to our understanding of intestinal neoplasia. [ABSTRACT FROM AUTHOR]

Immunological and epigenetic changes are interconnected and contribute to tumorigenesis. We determined the immunoprofiles and promoter methylation of inflammation-related genes for colitis-associated colorectal carcinomas (CA-CRC). The results were compared with Lynch syndrome (LS)-associated colorectal tumors, which are characterized by an active immune environment through inherited mismatch repair defects. CA-CRCs (n = 31) were immunohistochemically evaluated for immune cell scores (ICSs) and PDCD1 and CD274 expression. Seven inflammation-associated genes (CD274, NTSR1, PPARG, PTGS2, PYCARD, SOCS1, and SOCS2), the repair gene MGMT, and eight standard marker genes for the CpG Island Methylator Phenotype (CIMP) were investigated for promoter methylation in CA-CRCs, LS tumors (n = 29), and paired normal mucosae by multiplex ligation-dependent probe amplification. All but one CA-CRCs were microsatellite-stable and all LS tumors were microsatellite-unstable. Most CA-CRCs had a high ICS (55%) and a positive CD274 expression in immune cells (52%). NTSR1 revealed frequent tumor-specific hypermethylation in CA-CRC and LS. When compared to LS mucosae, normal mucosae from patients with CA-CRC showed significantly higher methylation of NTSR1 and most CIMP markers. In conclusion, CA-CRCs share a frequent ICShigh/CD274pos expression pattern with LS tumors. Elevated methylation in normal mucosa may indicate field cancerization as a feature of CA-CRC-associated tumorigenesis. [ABSTRACT FROM AUTHOR]